1. Field of the Invention
The present invention relates to a group III nitride compound semiconductor light-emitting device.
The present application is based on Japanese Patent Application No. 2000-208070, which is incorporated herein by reference.
2. Description of the Related Art
Group III nitride compound semiconductors are used in a light-emitting device such as a light-emitting diode or the like. Such a light-emitting device is configured so that group III nitride compound semiconductor layers having a device function are epitaxially grown on a surface of a substrate, for example, made of sapphire. For example, a light-emitting diode is configured so that an n-type clad layer, a light-emitting layer and a p-type clad layer are laminated successively on a substrate. Because the sapphire substrate has electrically insulating characteristic, both positive and negative electrodes need to be taken out from one surface side. To provide the negative electrode (n-type seat electrode), a contact layer is formed under the n-type clad layer and partially revealed by etching. Because the p-type group III nitride compound semiconductor layer generally has high resistance, it is impossible to disperse an electric current on the whole region of the p-type clad layer when the positive electrode (p-type seat electrode) is merely provided on the p-type clad layer.
In the background art, therefore, a light-transmissible electrode is attached onto the whole surface of the p-type clad layer. A p-type contact layer may be further provided between the light-transmissible electrode and the p-type clad layer.
Light emitted from the light-emitting layer passes through the p-type semiconductor layer and the light-transmissible electrode and goes out to the outside. That is, the light-transmissible electrode is disposed to face the direction of the optical axis, so that the light-transmissible electrode serves as a light emission observation surface.
A higher light emission output is required of the light-emitting device. Therefore, various improvements have been made. Paying attention to the fact that the quantity of light emitted in the lateral direction of the device is large, the inventor of the present invention has conceived a configuration in which light emitted from a side surface of a device is reflected efficiently toward the direction of the optical axis.
The configuration is that a groove is mechanically provided in the circumferential edge of the device so that light emitted in the lateral direction of the device from a light-emitting layer revealed in the groove is reflected toward the direction of the optical axis by use of a side surface of the groove.